US2374208A - Heat exchanger - Google Patents

Description

April 24, 1945. Ik. s. JONES, JR

HEAT EXCHANGER Filed April 20 NNNNNNNWNNNNNNNNNNNNNNM Www, @Suk Sgm neared am, at, rece NHTED STATES PATE; OFI-HCE HEAT EXCGER l Russell S. jones, Jr., Chicago, Ill., assignor -to Niagara Blower Company, New York, N. Y.,'a

corporation of New York 5 'Application April 2 0, 1942, Serial No. 439,621

Y l Claims. This invention relates to a heat exchanger andmore particularly to a heat exchanger which is primarily employed to cool industrial liquids and which is also employed, during cool weather, to heat the air in the industrial plant or factory through heat derived from the industrial liquid being cooled.

The conventional method of cooling such industrial liquids has long been to pass the liquid through shell and tube or double pipe heat vexchangers where the heat was taken up by water which had been previously cooled in a .cooling tower or spray pond or which required cold wells,

`orthe costly consumption of city water, vThis required a large amount of apparatus and is' difcult to expand in j capacity without costly additions to the System.

In the heat exchanger forming the subject. of the present invention the .air is drawn by fans through a casing containing coils through which the hot industrial liquid is passed, the liquid being kept in a closed system. A'Simultaneously the coils are drenched by dense sprays of water, the

evaporation of which, as it strikes the hot coils,

so greatly increases the heat transfer that the equipment is much more compact than conventional systems as above described and can be conveniently located near the Work either indoors or out. to be cooled can be brought down to a point very near to the wet bulb temperature of the outside air Without mechanical refrigeration. Only a small amount of the spray water is evaporated and removed with the leaving air. The rest falls into a tank and is recirculated through the sprays, so that the loss of water is only about v of that used in continuous iiow cooling.

It is the principal object of the present invention to provide such an evaporative type heat exchanger for cooling industrial liquids in which the apparatus is employed, during cool weather,

The temperature of the industrial liquid- 5,`.exact control of the temperature of thelheated air delivered into the factory building beplant. Another object of the invention is to provide such a heat exchanger in which the humidity of y w the `air delivered to the factory building or plant l0 during cool weather is under exact control.

vOther objects arel to provide a heat exchanger accomplishing 'the above which is relatively sim- V-ple in construction and operation and which will stand up under conditions of severe and constant'use without getting out of order or requiring repairs. Y

In the accompanying drawing: Fig. .`1 is a side elevationof a heat exchanger embodying the present invention.

Fig. 2 is a vertical transverse section, on an to heat and deliver Vair into the factory building or plant thereby to heat the factory building or plant through heat derived from the industrial liquid being cooled with a resultant saving in the cost of heating the factory building or plant. Another object of the invention is to provide y such a heat exchanger which is entirely automatic in changing from its function of evaporative cooling to air heating, the apparatus being Adesigned to automatically shift from one function tothe other when the temperature of the air passing through the apparatus reaches F.

Another object of the invention is to provide such a heat exchanger inwhich the minimum enlarged scale, this section being taken on line 2 2, Fig. 1.

The heat exchanger is shown in the drawingas including a sheet metal casing 5 which is formed at its base to provide a tank 6, this tank 6 containing a body of water l which is Aevaporated'to v provide the cooling effect during warmer weather.

The tank 6 is preferably extended beyond one end ofthe casing 5, as indicated at 8, and this extension is provided with a top 9,

A plurality of fan housings Il) are mounted inthe upper part of the casing v5, the inlets of these fan housings being in communication with the interior of the casing ilso as to exhaust air therefrom. A common shaft II-extends through the several fanhousings I0 and is shown as driven by a motor I2 mounted on a bracket I3 at one end of the casing 5. Withineach fan housing the shaft II carries a fan wheel I4, these fans' drawing the air rom the interior of thecasing and discharging it through the outlets I5 of the several fan lhousings which-project upwardly through the top of the casing 5. 'I'he outlets I5 of the several fan housings IIJ are shown as connecting with a -comm'on casing or manifold I6,

this manifold having a vertical upwardly extending exhaust duct Il which leads to 'the outside of the building in 4which the apparatus is located and also having a horizontal duct I8 which leads to the room or other enclosure to be heated during 'cool weather.

The discharge of vthe air either through the' exhaust duct Il or thesupply duct Ito the room or-enclosure to; be heated is controlled by a plurality of exhaust air dempers 20 in the exhaust duct I1 and a plurality of room air dampers 2| in the duct leading to the room or other enclosure to be heatedz/ Each of these groups of dampers is connected -to work in unison and the two groups are actuated by a damper motor 22, this damper motor 22 having a link connection with the exhaust dampers .and also having a link connection 24 with the room air dampers 2|, the damper motor 22 acting to open one set of dampers and to close the other set ofdampers in the manner hereinafter described.

Air is admitted to the bottom of the casing 5 through an .air inlet which connects with an air inlet box 3| having a fresh or voutside air duct 32'leading to the outside and a room air duct 33 communicating with the room l or enclosure in which the apparatusis placed. A plurality of outside or fresh air dampers 34 are provided in the outside or fresh air duct 32 and a plurality of room air dampers 35 are arranged in the room air duct 33. Each set of these dampers is interconnected to work in unison and the two sets of dampers are cross connected by a link 35 so as to work in-opposition to each other, the fresh air dampers 34 closing when the room air dampers 35 open and vice versa. 'I'he two sets of damp-y ers 34 and 35 are operated by a damper mo tor 31.

The water 1 to the tank 6 can be supplied through a float valve 43 and theftank 6 is shown as provided with an overflow pipe 42 and a drain pipe 43. This water 1 is used to provide the spray water for drenching the bank of coils 45 through which the industrial liquid to be cooled yis passed, this bank of coils being shown as provided with an inlet line 46 and. an outlet line 41 extending through one end wall of the casing 5. The water lfor spraying the bank o1' cooling coils 45 is shown as withdrawn from the tank 6 through the inlet 50 of a pump 5I which is shown as mounted on the top wall 9 of the ex- Vtension 8 and as having a vertical outlet pipe 52 :connected with a horizontal pipe 53 extending lengthwise through the interior `of the casing 5 above the bank of cooling coils 45. This hori- Azontal pipe 53 is shown as carrying a suitable number of branch pipes 54, each of which carries a plurality of downwardly discharging nozzles 55. The nozzles 55 are arranged above the bank of Icoils' 45 which carry the industrial liquid to be cooled so that these coils are constantly flushed line 61 under control of a diaphragm valve 63,l

the line 61 Ibeing shown as connecting with a plurality of branch lines 63 within the casing 5 carrying spray heads 16. The operation of the diaphragm valve 68 is shown as being under control of a hygrostat 1| arranged in the room or other enclosure which is to be heated during cool weather.

In the operation of the heat exchanger, as above described, it is assumed that the motor I2 is constantly runningso as to operate the fan wheels I4 and it 'is also assumed that a stream of the industrial liquid to be cooled is being supplied to the cooling coil 45 through its inlet and o'utlet 46 and 41. During warm weather conditions, that is, when the `outside temperature is above 45 F., at which time no heating of the air in thev factory building or plant is required, the apparatus operates as an evaporative cooler to cool the hot industrial liquid passing through the bank of coils 45, the humid air resulting from the evaporation of the spraywater on these coils being discharged back outside through the exhaust duct I1. For this purpose, at temperatures above 45 F., the thermostat 60, through its control line 6|, holds the damper motor 31 in the position in which the fresh air dampers 34 are held fully open and the room air dampers 35 fully closed. At the same time the thermostat 66, through its control line 62, holds the damper motor 22 in the position in which the exhaust air dampers 20 are held fully open and the room air dampers 2| fully closed. At the same time, the thermostat 60, through its control line 63, actuates the controller 64 to energize the motor of the pump 5|. With this setting of the thermostat it will therefore be seen that the continu-v haust dampers 20 are opened and the room air dampers 2| closed, all of this air is discharged into the exhaust duct I1, back to the outside.

Since at this time the spray water pump 5| is operating, spray water 1 from the pan 6 is with- 36 to the casing 5. For this purpose one branch line 6| from the thermostat 60 leads to the damper motor 31 controlling the fresh air dampers 34 and room air dampers 35; another branch line 62 `from the thermostat 60 leads to the damper motor 22 which controls the exhaust dampers 26 and the room air dampers 2| and another branch 63 leads to a controller-*64 onthe motor of the spray water pump 5|.

To prevent entrained'water from being drawn into the fan housings I0 and discharged, a series of eliminator plates 65 lis provided above the sprays` 56. In order to 'provide for control of the humidity of the air delivered-4 to `the enclosur or room ito be heated during cool weather, a systeni or humidifying sprays 66 is shown as provided immediately below the eliminator plates 65.

These sprays 66 are supplied with water from a 7s drawn by this pump and discharged through the vertical line 52, longitudinal pipe -53 and branch lines 54, through the spray nozzles 55, this spray water drenching the bank of cooling coils 45 through which the hot industrial liquid is passing. This water evaporates upon the cooling coils 45 and reduces the temperature of the industrial liquid passing therethrough to a temperature very near to the wet b ulb temperature of ,the outdoor air which is drawn into the casing 5.

When the temperature of the outside air'drops to approximately 45 F., the thermostatl 66,

through its outlet line 63, deenergizes the motor of the spray water pump 5| so that the spraying of the coils 45v is discontinued. At the Sametime this thermostat 60, through its outlet line 62. actuates the damper motor 22 -s'o as to close the exhaust air dampers 20 and open the room air dampers 2|.` Under this condition of operation freshair is drawn in through the fresh air duct 32, past'the thermostat 66 and into the bottom of the casing 5, This relatively cold air is then' drawn up through the cooling coil 45 where it humidity in the'enclosure.v

operates to cool the hot industrial liquid passing through this bank oi' coils. This air is heated upon passingthe coil 45 and is discharged by the fan wheels I4 through the room air duct I8 so as to heat the factory :building or plant and thereby conserve fuel. In this operation it will be noted that thesprays 56 are not in operation since otherwise the air delivered to the room would Ibe substantially saturated and hence would' be undesirable for all normal processing.

Upon a further drop of the outside air temperature, the thermostat 60, through its control line 6I, actuates the damper motor 3l to progressively close the fresh air dampers 34 vand open the room air dampers 35 to a greater de- By this means the dampers 34 and 35 operate as mixing dampers, the thermostat 60 automatically setting these dampers in the position in which the air'drawn'into the casing 5 is at a temperature of approximately 45 F. Thus, in extremely cold weather very little fresh air would be admitted through the fresh air duct 32 and a relatively large proportion of room air would be admitted through the room air duct 33 so that the temperature of the air delivered into the bottom of the casing is maintained at approximately 45F.

During cold weather operation, especially at low outside air temperatures, it is desirable that the air delivered by the apparatus be at the desired relative humidity to maintain the proper air conditions in the enclosure heated by the apparatus. For this purpose, when the relative humidity within the enclosure drops below the setting of the hygrostat 1|, this hygrostat opens the diaphragm valve 68 so as to admit water from i the water supply line 6l to the spray nozzles l0.

These nozzles are relatively few in number, but the evaporation of the water discharged therefrom serves to humidify the passing air .to the desired extent to maintain the desired relative It will be seen that by the provision of separate humidifying nozzles under control of the hygrostat il the desired minimum relative humidity is maintained in the enclosure. It will further be seen that this humidity control is entirely automatic in its operation inasmuch as humidication of the air in the enclosure is only called for when the apparatus is used as a heater for the air delivered to the enclosure.

From the foregoing it will be seen that the present invention provides an evaporative heat exchanger for cooling hot industrial liquids which is also used for space heating.. The main disadvantage to the use of such units for space heating has been that the amount of moisture contained in the air has been excessive and objectionable from a heating standpoint. It will be seen that this objection has been overcomeby rendering the sprays inoperative when the apparatus is u sed for space heating, the only operative sprays being the humidifying sprays which are under hygrostat control. It will further be Seen that'the heat exchanger is entirely automatic in becoming operative and inoperative as a space heater andl that thetemperature of the air employed in charging and distributing water over said cooling coil to Wet the exterior of said cooling coil and means to deflect the air from said air outlet into said exhaust duct when said discharging and distributingmeans are rendered operative and to deect the air from said air outlet into said warm air duct when said discharging and distributing means are rendered inoperative.

2. In a heat exchanger for cooling a stream of liquid an'd having a casing provided with an air inlet and an air outlet, a cooling coil in the stream of air passing through said casing', means for discharging and distributing water over said cooling coil to wet the exterior of said cooling coil and to evaporate and absorb heat therefrom and means for conducting-said stream of liquid to be cooled through said cooling coil; an exhaust duct connected with said air outlet and leading to the outside, a warm air duct connected with said air outlet and leading to an enclosure, means for deecting a substantial quantity of the air from said air outlet alternately into said exhaust duct and said warm air duct, control means for rendering said discharging and distributing means operative andinoperative, and thermostat means responsive to the outside air temperature and actuating said control means and said deflecting means to deflect the air from said air outlet into said exhaust duct when said discharging and distributing means are rendered operative and to deflect the air from said air outlet into said warm air duct when said discharging and distributing means are rendered inoperative.

3. In a heat exchanger for cooling a stream ofy l liquid and having a casing provided with an air` inlet and an air outlet, a cooling coil in the stream of air passing through saidv casing, means for discharging and distributing water over said cool- A ing coil to wet the exterior of said cooling coil outside, a warm air duct connected with said air.

outlet and leading to an enclosure, `means for deecting a substantial quantity of the air from said air outlet alternately into saidexhaustuct and said warm air duct, control means for rendeiingsaid discharging and distributing means operative and inoperative, and thermostat means arranged in saidair inlet and actuating saidcontrol means and said delecting means to-'defiect f the air from said air outlet into said exhaust duct when said discharging and distributing means are' rendered operative and to deflect the air from said air outlet into said warm air duct when said discharging and distributing means are rendered inoperative.

`4. In a heat exchanger for cooling a stream of liquid and having a casing provided with an loutside air.. inlet `and an air outlet, means for ymoving a -stream of air through said outside air inlet, casing and air outlet, a cooling coil in the,v

streamof air' passing through said casing, means for discharging and distributing water towet the to evaporate and absorb heat therefrom and.

exterior of said cooling' coil and to evaporate and absorb heat therefrom and means for conducting the said stream of liquid to be cooled through said cooling coil; an air exhaust duct connected with said air outlet and'leading'to the outside, a warm air duct connected with said air outlet and leading to an enclosure, means for defiecting a .sub-

stantial quantity of the air from said air outlet' alternately into said exhaust duct and said warm air duct, control means for rendering said discharging and distributing means operative and inoperative, and thermostat means responsive to the outsidev air temperature andactuating said control means andsaid deflecting means -to deiiect the air from said air outlet'into said exhaust duct and to render said discharging and distributing means operative at outside air tem-- peratures above approximately 45 F. and to deilect the air from said air outlet into said wann air duct and to render said discharging and distributing means' inoperative at outside air temperatures below approximately `45 F.

5. In a heat exchanger for cooling a stream of liquid and having a casing provided with an' air inlet and an air outlet, means for moving a.

stream of vair through said air inlet, casing and air outlet, a cooling coil in the stream of air passingthrough said casing, means for discharglng and distributing water to wet the exterior of said cooling Acoil and to evaporate and absorb heat therefrom and means for conducting the.

said stream of liquid to be cooled through said `cooling coil; an air 'exhaust duct connected with` said air outlet and leading to the outside, a warm air duct connected with said air outletand leading to an enclosure, means for deiiecting a sub.; stantial quantity of the air from said airoutlet alternately into said exhaust duct and said warm airl duct, an outside air duct connected withsaid air inlet, a return air duct connected with said air means for varying the proportions oi outside and vreturn air admitted through said. air inlet from said outside air duct and said return air duct, control means for rendering said discharging and' distributing means' operativey and .inoperative, and thermostat means actuating said control means, ysaid deilecting means and said mixing means, at outside air temperatures above 4 a predetermined point, to deflect the air from said air outlet intosaid exhaust duct, to render said discharging and distributing means operative and to admit outside air exclusively into said air inlet and, at outside air temperatures below said predetermined point, todeilect the air from said air outlet into said warm air duct, to render' saiddischarging and distributing means inoperative and to admit return air from saidreturn air duct into said airinlet.

7. In a heat exchanger for coolingastream of liquid and having a' casing provided with an air inlet and an -air outlet, means' for moving a stream of air through said air inlet, casing and air-outlet, a cooling coil in the stream of a pass- "ing through said casing, means for disc arging and distributing `water to wet the exte or of i said cooling coiland to evaporate and absorb q Vheat therefrom and means for conducting the saidstream of liquid to be cooled through said f ing t9 an enclosure, means for deecting a subinlet and leading' from lsaid enclosure, mixing Y means for varying the proportions of outside and return air admitted through said air inlet from said outside air duct4 and said return air duct, control means for rendering said discharging and distributing means operative land inoperative, and

` thermostatmeans actuating said control means .and said deilecting means to deflect the air from said air outlet into said exhaust duct and to render saidfdlscharging and distributing means operative at outside air temperatures above a predetermined point and to deilect the air from said air outlet into said warm air duct and to render said discharging and distributing means inoperative at outside air temperatures below said pre-A determined point.

6. In a `heatvexchanger for cooling a stream of liquid and having a casing provided with an air inlet and an air outlet, means for moving a stream of air through said air inlet, casing and air outlet, a cooling coil in the stream of air passing through said casing, means'forv discharging cooling coil and to evaporate and absorb heat therefrom and means for conducting the said stream of liquid to be cooled through said cooling coil; an air exhaust duct connected with said air outlet and y(leading to the outside, a warm air ,duct connected with said air outletv and leading to an enclosure, means for deilecting a substantial quantity of the air from said air outlet alternatly into said exhaust duct and said warm vair duct, an outside air duct connected with' said air inlet, a returnair duct connected with said and distributing water to'wet the exterior of said cooling coil; an air exhaust'duct connected with said air outlet and leading to the outside, a/warm Yair duct connected with said air outlet and leadstantial quantity of the air from saidair outlet alternately into said exhaustduct and said warm air duct, an outside air duct connected with said' ilecting Imeans and said mixing means, at out- A side air temperatures above.` a predetermined.

point, to deilect the air from said air outlet into said exhaust duct, to render said discharging and distributing means operative and to admit outside, air exclusively into saidair inlet and, at outside air temperatures below said predetermined pointf, to deflect the'air from said 'air uoutlet into said warm air duct, tolrender said discharging andfdistr'ibuting means in operativearidv to admit return air from said return air duct into said air inlet in anamount sunlclent to maintain the temperature of the air admitted through said air inlet at approximately said rpredetermined point.

8. In a heat exchanger for cooling a stream of liquid and having .an elongated uprlghtcasing which is closed at its lower end to provide a pan and is provided immediately above said pan with4 van air inlet 'and at its .upper end wlth an air outlet, a fan in the upper part of said casing for moving a streamuof air through said -air inlet, casing and air outlet, a cooling coil -in said casair inlet and leading from said enclosure, 75.

ingbetween said air -inlet and said fan and through which said stream ofair passes, a plurality o f spray nozzlesarranged to discharge and Y distribute waterv yto wetthe exterior of said coil and to evaporate and absorb heat therefrom, the

excess of said spraywater collecting in-said pan and a pump recirculating said collected spray water through said spray nozzles and means for conducting the saidV stream of liquid to be cooled through said cooling coil; an air exhaust duct connected with said air outlet and leading to the outside, a Warm air duct; connected with said air outlet and leading to an enclosure, means ior de'lecting a substantial quantity of the air from said air outlet alternately into said exhaust duct and said warm air duct, an outside air duct connected with said air inlet, a return air duct connected with said air inlet and leading from said enclosure, mixing means for varying the proportions of outside and return air admitted /t rough said air inlet from said outside air duct and said return air duct, control means for rendering said pump operative and inoperative, and thermostat means in said kair inlet and actuating said control means, said deecting means and said mixing means, at outside air temperatures above apredetermined point, to deilect the air from said air outlet into said exhaust duct, to render said pump operative and to admit outside air exclusively into said air inlet and, at outside air temperatures below said predetermined point, to ydeflect the air from said air outlet into said warm air duct, to render said pump inoperative and to admit return air from said return air duct into said air inlet in an amount suiicient to maintain the temperature of the air admitted through said air inlet at approximately said predetermined point.

9. ln a heat exchanger for cooling a stream of liquid and having a casing provided with an air inlet and an air outlet, a cooling coil in the stream of air passing through wsaid casing, means for discharging and distributing water over said cooling coil to wet the exterior of said cooling coil and to evaporate and absorb heat therefromA and means for 'conducting said stream of liquid to be cooled through said cooling coil; an exhaust duct connected with said air outlet and leading to the outside, a Warm air duct connected with said air outlet and'leading to an enclosure, means for deilecting a substantial quantity of the air from said air outlet alternately into said exhaust `duct and said Warm air duct, control means for rendering said discharging and distributing means operative andinoperative, thermostat means .actuating said control means and said deflecting 'means to deflect the air from said'air outlet into said exhaust duct when said discharging and distributing vmeans arerendered operative and to deect the air ing through' said casing, means for discharging and distributing Water to wet the exterior of said cooling coil and to evaporate and absorb heat therefrom and means for conducting the said stream of liquid to be cooled through said cooling coil; an air exhaust duct connected with said air outlet and leading to the outside,l a Warm air duct connected With said air outlet and leading to 'an enclosure,-means for deecting a substantial quantity of the air from said air outlet alternately into said exhaust duct and said warm air duct, an outside air duct connected with said air inlet, a return air duct connected with said air inlet and leading from said enclosure, mixing means for varyingthe proportions .of outside and return air admitted through said al1' inlet from said outside air duct and said return air duct, control means for rendering said discharging and distributing means operative and inoperative, thermostat means in said air inlet and actuating said control means, said deecting means and said mixing means, at outside air temperatures'above a predetermined point, to defleet the air from said air outlet into said exhaust duct, to render said discharging and distributing means operative and to admit outside air exclusively into said air inlet and, at outside air temperatures below said predetermined point, to deect the air ironi'said air outlet into said warm air duct, to rendersaid discharging and distributing means inoperative and to admit return air from said return air duct into said air inlet in an amount sufcient to maintain the temperature of the air admitted through said air inlet at approximately said predetermined point, means for humidifying the stream of air passing' through said casing and means responsive tothe humidity of the air'in said enclosure and regulating said humidifying means.

t RUSSEIL'S. JONES, Jn.

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